1. Field of the Invention
The present invention relates to a disk reproducing device reproducing a signal recorded in a disk such as an optical disk, and more particularly to a disk reproducing device capable of reducing errors of reproduction signals.
2. Description of the Background Art
A method of adjusting reproduction signals of a disk reproducing device of interest to the present invention is disclosed, for example, in Japanese Patent Laying-Open No. 11-328858. FIG. 7 is a block diagram showing a main part of a disk reproduction signal processing portion disclosed in this publication.
Referring to FIG. 7, in the conventional disk reproducing device, an RF (Radio Frequency) signal 109 that is a disk reproduction signal from a reproducing head is amplified by a preamplifier 101 and is then output to an AGC (Automatic Gain Control) & equalizer 102. AGC & equalizer 102 absorbs reduction in the output and holds the gain constant of RF signal. A high frequency enhancing filter (equalizer) is used to remove a high frequency noise of RF signal 109 and to boost the vicinity of a high frequency component of RF signal 109 having an amplitude extremely deteriorated due to interference between codes, for waveform equalization. Thereafter, RF signal 109 is binarized in slicer 103 and a clock signal 111 is separated in a PLL (Phase Locked Loop) 104. Binarized synchronous data 112 is generated from clock signal 111 and binarized data 110. A voltage is applied to the equalizer as a boost voltage value 114 in order to specify a boost amount. A phase error pulse 113 output from PLL 104 is converted to a phase error voltage 115 in a voltage conversion circuit 105. An A/D (Analog/Digital) converter 106, a CPU (Central Processing Unit) and a D/A (Digital/Analog) converter 108 adjust phase error voltage 115 to the minimum for output as a boost voltage amount 114.
Conventionally, a reproduction signal of an optical disk has been adjusted as described above. A boost amount of the high frequency enhancing filter (equalizer) has been adjusted with phase error voltage 115 adjusted to the minimum value. Unfortunately, with only adjustment of boost amount, the error correction for an individual disk is not sufficient.
In addition, since slicer 103 conventionally has a fixed binarization slice value, an optimum correction for each disk cannot be carried out.